目的 评价新型超声工作尖对牙根面的影响，为其临床应用提供依据。 方法 收集因重度牙周炎无法保留需拔除的前牙27颗，随机分为3组：新型超声工作尖组（n=9）、DENTSPLY超声工作尖组（n=9）、EMS超声工作尖组（n=9）。处理前利用表面粗糙度测量仪测量3组离体牙牙根表面粗糙度。体外模拟牙周基础治疗操作，去净离体牙表面牙结石后再次测量牙根表面粗糙度。制成牙切片通过扫描电镜法观察镜下牙根面形态。3组样本牙根粗糙度的组间对比使用方差分析，事后检验使用最小显著性差异法（least significant difference，LSD），组内对比采用配对t检验，以P<0.05为差异具有统计学意义。采用SPSS 24.0对数据进行分析。 结果 根面粗糙度检测结果：3组样本的牙根粗糙度变化值有显著差异，EMS超声工作尖组表面粗糙度值较处理前下降最小，其次是DENTSPLY超声工作尖，新型超声工作尖表面粗糙度值较处理前下降最显著（P<0.001）。扫描电镜观察：使用EMS超声工作尖进行牙周基础治疗后的牙根面形态最不完整，可见细小凹坑状缺损，部分区域有牙骨质剥脱和穿凿孔洞，有较多的玷污层和碎屑残留；使用DENTSPLY超声工作尖进行牙周基础治疗后的离体牙根面相较于EMS超声工作尖组更光滑，有玷污层和少许碎屑残留，表面可见细小裂纹，牙根面不连续；使用新型超声工作尖进行牙周基础治疗后的离体牙根面较DENTSPLY超声工作尖组更为平整，牙骨质形态结构清晰、完整、连续，有少量线性划痕，未见明显牙骨质剥脱或凿孔。 结论 新型超声工作尖进行牙周基础治疗后，牙根表面光滑；新型超声工作尖对牙根面损伤小，是理想的超声工作尖。

Objective To evaluate the effect of new ultrasonic scaler tip on tooth root surface and to provide a basis for its clinical application. Methods A total of 27 anterior teeth that needed to be extracted due to severe periodontitis were collected and randomly divided into three groups： the new ultrasonic scaler tip group（n=9），DENTSPLY ultrasonic scaler tip group（n=9），and EMS ultrasonic scaler tip group（n=9）. Before treatment，the surface roughness of the three groups of extracted teeth roots was measured with the surface roughness measuring instrument. Initial periodontal therapy was simulated in vitro. The tooth root surface roughness was measured again after removing the calculus on the extracted tooth surface. Tooth sections were prepared for observation of the root surface morphology using scanning electron microscopy. Analysis of variance was used for inter-group comparison of root roughness. Least significant difference method was used for post hoc test. Paired t-test was used for intra-group comparison. A P value of <0.05 indicated a statistically significant difference. SPSS 24.0 was used for data analysis. Results 1. Root surface roughness test showed a significant difference in the changes of roughness among the three groups. The surface roughness of EMS ultrasonic scaler tip group decreased the least compared with that before treatment，followed by DENTSPLY ultrasonic scaler tip group. The surface roughness of the new ultrasonic scaler tip group showed the most significant decrease compared with that before treatment（P<0.05）. 2. Scanning electron microscope observation showed that the morphology of the root surface after initial periodontal therapy with EMS ultrasonic scaler tip was the most incomplete，with small pit-like defects，cementum denudation and drilling holes in some areas，and abundant smear layers and debris residues. Compared with the EMS ultrasonic scaler tip group，the extracted root surface after initial periodontal therapy with DENTSPLY ultrasonic scaler tip was smoother，with less smear layer and a few debris residues，fine cracks on the surface，and discontinuous root surface. After initial periodontal therapy with the new ultrasonic scaler tip，the extracted root surface was more flat than that of DENTSPLY ultrasonic scaler tip group，with clear，complete，and continuous cementum morphology and structure，a few linear scratches，and no obvious cementum denudation or drilling holes. Conclusion The extracted tooth root surface is smooth after initial periodontal therapy using the new ultrasonic scaler tip. The new ultrasonic scaler tip is the ideal ultrasonic scaler tip with less damage to the tooth root surface.